If you attempt to guess one number chosen from 49 lottery balls then the
probability that you are correct is 1/49. If you have a second attempt, and the
previous ball is not replaced, then the probability is 1/48.
If you choose six numbers then the probability that one of them is the same as the
first ball drawn is 6/49. Given that the first number is chosen correctly then the
probability for drawing the second number correctly is 5/48.
The probability of choosing all six numbers correctly is:
6 / 49 x 5 / 48 x 4 / 47 x 3 / 46 x 2 / 45 x 1 / 44 = 1 / 13,983,816
So, for example, if you have one thousand attempts per day then you could expect to win, on average,
once during the next 38 years!